Application Cases

In ultrasonic guided wave-based structural health monitoring (SHM), transducers serve as both actuators and sensors. Actuators primarily convert external input energy (e.g., electrical energy) into mechanical energy, inducing compressive vibrations in the structure to generate stress waves. Sensors, on the other hand, detect stress waves within the structure and convert this information into other forms such as electrical or optical signals for output, reflecting the structural condition. Sensors are driven by power amplifiers.

A Lamb wave-based health monitoring system includes hardware components, hardware-software interaction, and damage monitoring software. The hardware module of the health monitoring system is illustrated in the figure below, with its working principle as follows:

Figure: Experimental Principle

In the system control module, an appropriate excitation signal is designed and sent to the signal generation module, which produces a low-voltage analog excitation signal. This signal is then amplified by the power amplifier module and transmitted to the channel switching module. The channel switching module selects a suitable piezoelectric transducer from the transducer array to apply the amplified voltage signal, thereby exciting Lamb waves in the plate structure. Other piezoelectric elements in the transducer array act as sensors to detect Lamb waves in the structure, converting the strain state into voltage signals that are fed back to the channel switching circuit.

The signal conditioning module amplifies and filters the collected voltage signals before transmitting them to the data acquisition module, which converts the analog signals into digital signals. These digital signals are then sent to the system control module for data analysis and processing.

Lamb Wave-Based Steel Plate Damage Monitoring System Experimental Platform:

Figure: Experimental Platform

Experimental Procedure:
A computer-controlled signal generator produces a sinusoidal signal with a voltage amplitude of 3V and a frequency of 50 kHz. This signal is amplified 40 times by the power amplifier ATA-4052. The amplified voltage signal is then sent to the channel switching circuit, which selects an appropriate piezoelectric transducer to excite Lamb waves in the structure. Apart from the excitation element, other transducers in the array sense the Lamb wave signals and transmit the corresponding response signals to the channel switching circuit. The channel switching circuit sequentially routes the sensor responses to the signal conditioning circuit, where the voltage signals are amplified 100 times and filtered within the range of 500 Hz to 200 kHz. The data acquisition card collects the signals, inputs them into the controller for storage and processing, and ultimately produces the damage monitoring results.

Figure: ATA-4052C High-Voltage Power Amplifier Specifications and Parameters